Installing barebox for karo-tx53

[Dr. Patrick Langfeld]

Hi,
I want to install barebox on a Karo TX53 module as a primary bootloader.
Now I have a few questions:

a)
With wich version should I start. I found the branch karo-tx53 at 
git://github.com/gchiii/barebox-tx53.git
Is this the right one (as it seems to be quit old with latest commit 9 
month ago)

Or should I start with the master branch at 
git://git.pengutronix.de/git/barebox.git ?

b)
Is there even a simpler way as I am using ptxdist?

c) How can I flash barebox over u-boot, which is my current bootloader?

Best regards
Patrick